1. Field of the Invention
The invention relates to a latch mechanism and/or a quick-connect coupling usable with an automatic water docking system which facilitates docking and which inhibits or prevents rack flooding.
2. Discussion of the Related Art
It is desirable to supply drinking water to laboratory animals or the like reliably and automatically upon demand. Such water is typically supplied to animals housed in cages docked to a water manifold of a rack system.
One such cage and rack system is disclosed in U.S. Pat. No. 5,042,429 to Deitrich et al. (the Deitrich patent) The system disclosed in the Deitrich patent houses a plurality of laboratory animals in rows of cages supported on shelves of a rack. The cages are supplied with water by a common water manifold and with air by a common air manifold.
Watering systems of the type disclosed in the Deitrich patent must accommodate frequent removal of the individual cages from the rack, e.g., for testing animals housed therein or for cage cleaning. Such systems usually also seek to minimize cross-contamination of the animals housed in the various cages. Deitrich attempts to accommodate these requirements by connecting each of the individual cages of its system to the water manifold by a quick-connect coupling. This coupling includes, in the case of each cage, a watering valve fixed to the cage, a male fitting attached to the watering valve and extending inwardly from the cage, and a female fitting extending outwardly from the water manifold. The male fitting engages the female fitting with a friction fit when the cage is properly positioned on the rack. According to the Deitrich patent disclosure, the friction-fit type quick-connect coupling facilitates removal and replacement of the cages, and the internal watering valve prevents or at least inhibits cross-contamination between cages.
The friction-fit quick-connect coupling employed by the Deitrich patent, while facilitating removal and replacement of a cage, exhibits the disadvantage of not xe2x80x9clockingxe2x80x9d the cage in its docked position so that, if the cage is bumped or improperly positioned, the coupling may leak and/or fail to deliver water to the animal housed in the cage. While failing to deliver water to the animal is problematic because it could result in the dehydration or even death of the animal, leakage is an even greater problem because it could result in the flooding of several or even all of the cages on a rack and in the sickness or even death of all of the animals housed in those cages. The need therefore has arisen to provide a water docking system which, while facilitating removal and replacement of cages and preventing or at least inhibiting cross-contamination between cages, also reliably delivers drinking water without leakage to the animals housed in the cages.
One at least partially successful attempt to address this need is disclosed in U.S. Pat. No. 5,337,696 to Edstrom et al. (the Edstrom patent). The cage and rack system disclosed in the Edstrom patent inhibits unintended cage undocking by using a locking quick-connect coupling to connect the watering valve to the water manifold. The locking quick-connect coupling disclosed in the Edstrom patent has a collar on the female fitting which locks onto the male fitting when a plug of the male fitting is inserted into the female fitting and which must be manually retracted to permit subsequent uncoupling. Uncoupling is facilitated by a decoupler which may take the form of a lever mechanism or a cable mechanism leading from the front of the cage to the collar on the female fitting.
The docking system of the cage and rack system disclosed in the Edstrom patent inhibits leaks and assures the supply of water to animals once the male fitting of the quick-connect coupling is positively locked to the female fitting. However, certain characteristics of this system may be considered disadvantageous to some. For instance, it is difficult for the casual inspector to determine whether or not the male fitting is in fact locked to the female fitting unless he or she physically grabs the cage and pulls it towards him or her with some force. Moreover, both the locking quick-connect coupling and the associated decoupler are relatively expensive to manufacture. The decoupler also inhibits to some extent cage removal because a person who is removing the cage must first actuate a lever or cable mechanism to release the locking coupling, then remove the cage from the shelf.
In short, the system disclosed in the Edstrom patent represents a trade-off when compared to existing water docking systems employing friction-fit couplings. It provides a much more reliable and less leak-prone connection of the watering valve to the water manifold and effectively locks the cage in its docked position. However, these benefits come at the cost of increased complexity and reduced ability to remove the cage from the rack.
As discussed above, a problem associated with many prior art water docking systems, and particularly those using friction-fit couplings, is that the couplings used in such systems tend to leak unless the cage is maintained in a fully-docked position on the rack in which the plug of the male fitting is fully inserted into the bore of the female fitting. This leakage results from the fact that the plug of the typical male fitting seals against the female fitting only after it opens the internal valve of the female fitting. Accordingly, water may flow around the male fitting and leak out of the coupling for a brief time as the male fitting is being inserted into the female fitting. If the male fitting is left in this partially-inserted position, water flows past the male fitting and leaks out of the coupling on a continuous basis, flooding the cage and rack system.
Prior art attempts to solve the problem of coupling leaks focused on locking the coupling and/or cage in a position in which the male fitting was sealed against the female fitting. Leakage could still occur if these latches or other safety features were improperly used, failed, or were circumvented. Leakage could also occur if the internal seal of the coupling failed.
It is therefore a primary object of the invention is to provide a latch mechanism usable with or without a water docking system which interacts with a water coupling to prevent coupling leakage and consequent cage flooding and to help ensure the continuous supply of drinking water to animals housed in the cage.
In accordance with a first aspect of the invention, this object is achieved by providing a latch mechanism including an indicator assembly which provides an indication that the latch catch is disengaged from the front wall of the cage. The indicator assembly preferably comprises an indicator flag mounted on the pivot arm and a shield provided on the support plate, the shield preventing observation of the indicator flag when the pivot arm is in the first position and permitting observation of the indicator flag when the pivot arm is in the second position.
In accordance with another aspect of the invention, this object is achieved by providing a latch mechanism including a stationary support plate, a pivot arm, a latch catch, and a spring. The support plate is configured to extend at least generally in parallel with the sidewalls of the cage. The pivot arm has inner and outer ends and has front and rear faces. The inner end of the pivot arm is pivotally attached to the support plate so as to be swingable from a first position in which the pivot arm extends at least substantially in parallel with the support plate to a second position in which the pivot arm is not substantially parallel with the support plate. The latch catch extends inwardly from the front face of the outer end of the pivot arm, the latch catch engaging the front wall of the cage to hold the cage in the designated position when the pivot arm is in the first position and becoming spaced from the cage when the pivot arm is in the second position. The spring biases the pivot arm towards the first position.
A second primary object of the invention is to provide a water coupling which is usable with or without a water docking system.
Another object of the invention is to provide a water coupling which meets the second primary object of the invention and which incorporates a safety feature that prevents leakage by assuring that the male fitting of the coupling is sealed to the female fitting before the internal valve of the female fitting opens.
In accordance with yet another aspect of the invention, these objects are achieved by providing a quick-connect coupling which includes a female fitting and a male fitting. The female fitting includes a generally cylindrical body, first and second axially spaced seals, and a valve core. The body has inlet and outlet ends and has a bore formed therein which extends axially from the outlet end thereof towards the inlet end thereof. The seals are located in the bore, the second seal being located axially between the first seal and the outlet end of the body. The valve core is located in the bore between the first seal and the inlet end of the body and is capable of sealingly seating on the first seal. The male fitting includes a generally cylindrical plug. The plug 1) is dimensioned to fit in the bore in the female fitting of the coupling, 2) has an outer radial periphery, and 3) has a bore formed axially therethrough. The plug, the first and second seals, and the valve core are so dimensioned and configured that, when the plug is inserted axially into the bore in the female fitting from the outlet end thereof, 1) the outer radial periphery of the plug first slidably seals against the second seal, 2) the plug then lifts the valve core from the first seal, and 3) the outer radial periphery of the plug then slidably seals against the first seal.
Alternatively, the male fitting may be sealed to the female fitting by a combined seal that includes first and second portions separated from one another by a divider portion of reduced diameter when compared to the first portion and to the second portion. The second portion is located axially between the first portion and the outlet end of the body. The plug, the first and second portions of the seal, and the valve core are so dimensioned and configured that, when the plug is inserted axially into the bore in the female fitting from the outlet end thereof, 1) the outer radial periphery of the plug first slidably seals against the second portion of the seal, 2) the outer radial periphery of the plug then slidably seals against the first portion of the seal, and 3) the plug then lifts the valve core from the first portion of the seal.
The coupling may comprise a friction-fit quick-connect coupling in which the male fitting of the coupling engages the female fitting with a friction fit only.
Alternatively, the coupling may comprise an active locking quick-connect coupling in which female fitting includes 1) a collar slidably mounted on the body, and 2) a plurality of locking balls which are mounted in holes formed in the body. The locking balls engage recesses in the outer radial periphery of the plug of the male fitting of the coupling when the plug is inserted into the bore in the female fitting. The collar is movable from a first position in which it forces the locking balls into the recesses to prevent axial movement of the male fitting with respect to the female fitting to a second position in which it permits the locking balls to move out of the recesses to permit axial movement of the male fitting with respect to the female fitting.
Alternatively, the coupling may comprise a passive locking quick-connect coupling. In this case, an oversized locking O-ring on one of the female fitting and the male fitting engages a groove in the other of the female fitting and the male fitting upon full insertion of the male fitting into the female fitting, thereby providing a snap-fit effect. The resultant connection combines the benefits of 1) ease of connection of a friction fit coupling and 2) the security of a locking coupling.
Yet another primary object of the invention is to provide an improved method of docking a cage to and undocking the cage from the water manifold of a cage and rack system.
In accordance with yet another aspect of the invention, this object is achieved by providing a method which includes providing a cage and rack system having a docking system as described above, then positioning the cage in a docked position on the shelf in which the male fitting is inserted into the female fitting so as to be sealed against the female fitting and so as to permit water to flow through the female and male fittings from the manifold, and, during the positioning step, moving the latch catch of the latch mechanism from an unlatched position in which it is disengaged from the cage and permits removal of the cage from the shelf to a latched position in which it positively engages the front wall of the cage and holds the cage in the docked position.
The use of the inventive docking system permits a single hand to move the latch catch from the latched position to the unlatched position and to simultaneously grasp the catch with the hand at a location permitting removal of the cage from the shelf with the hand.
In order to prevent leakage and consequent cage flooding, additional steps preferably comprise, during the positioning step, 1) sealing the male fitting of the coupling against the female fitting, 2) lifting a valve core of the female fitting from an internal seal of the female fitting, and 3) sealing the male fitting against the internal seal.
Other objects, features, and advantages of the invention will become more apparent to those skilled in the art from the following detailed description and the accompanying drawings. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.